The increased use of high temperature equipment in industry has led to a corresponding increase in the use of suitable insulation which can withstand the high temperatures employed. Conventional high temperature installations such as furnaces, soaking pits, annealing furnaces, etc., are frequently constructed with walls and roofs of refractory brick. This results in a heavy massive structure which must be braced or supported with a suitable metal structure. Construction expenses are high, due to the high cost of the refractory brick needed and the requirement of skilled labor for the proper assembly of the brick. Once assembled, these brick-type constructions, aside from their high cost and weight, are by nature quite rigid and are prone to cracking and breakage, due to mechanical strains set up by thermal expansion. Extended startup heating periods may therefore be required to minimize thermal shock and, if repairs are needed, a long cooling period may be necessary before repairs can be started.
In recent years, the introduction of fibrous insulation materials as replacements for brick linings has considerably improved furnace construction and thermal efficiency while also reducing the costs of construction and permitting faster heating and cooling cycles without any damage by thermal shock. Fibrous insulation is now available which can withstand furnace temperatures ranging as high as 2300.degree. to 2700.degree. F. As an example, a furnace construction system of this type is described in U.S. Pat. No. 3,523,395, in which fibrous insulating materials are fastened to the interior walls of a high temperature chamber by means of composite metal and refractory pins, the insulation being retained on the pins by suitable washers engaging the heads of the pins. While other similar systems are known and have been satisfactory in the initial stages of furnace operation, the problem remains of providing an insulation attachment means that will provide continuous positive support despite any slow shrinkage of the fibrous insulation during extended periods of furnace operation. An attachment means which will withstand the heat of the furnace for extended periods and yet retain the insulation in place, regardless of the effects of insulation shrinkage or furnace wall vibration, is therefore desirable.